MIC2841AYMT TR Micrel Inc, MIC2841AYMT TR Datasheet - Page 10

• Manufacturer Part Number: MIC2841AYMT TR
• Description: IC LED DRIVR WHITE BCKLGT 10TMLF
• Manufacturer: Micrel Inc
• Type: Backlight, White LEDr

Specifications of MIC2841AYMT TR

• Constant Current: Yes
• Topology: Linear (LDO), PWM
• Number Of Outputs: 4
• Internal Driver: Yes
• Type - Primary: Backlight, Flash/Torch
• Type - Secondary: White LED
• Frequency: 500kHz
• Voltage - Supply: 3 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 10-TMLF®
• Operating Temperature: -40°C ~ 125°C
• Current - Output / Channel: 20mA
• Internal Switch(s): Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Efficiency: -
• Other names: 576-3471-2

High Current Parallel Operation
The linear drivers are independent of each other and can
be used individually or paralleled in any combination for
higher current applications. A single WLED can be
driven with all 4 linear drivers by connecting D1 through
D4 in parallel to the cathode of the WLED as shown in
Figure 11. This will generate a current 4 times the
individual channel current and can be used for higher
current WLEDs such as those used in flash or torch
applications. The current is set by the R
can be calculated by the following equation.
D is the duty cycle of the LED current during PWM
dimming. When the device is fully on the duty cycle
equals 100% (D = 1). Figure 12 shows the response
time of the four paralleled linear drivers configured for
800mA to the enable signal, while Figure 13 shows the
turn off response. With a R
linear driver is set to 250mA, with all 4 linear drivers
connected in parallel, the MIC2841A is capable of
driving a total current of 1.0A.
Micrel Inc.
June 2009
C1
Figure 11. High Current LED Driver Circuit
I
LED
(mA) = 4 * 410 * D / R
R
END
V
SET
IN
U1 MIC2841AYMT
Control
PWM
SET
resistor of 1.65kΩ, each
SET
Dropout
Linear
Driver
Low
(kΩ).
SET
resistor, and
10
Input Capacitor
The MIC2841A is a high-performance, high bandwidth
device. Stability can be maintained using a ceramic input
capacitor of 1µF. Low-ESR ceramic capacitors provide
optimal performance at a minimum amount of space.
X5R or X7R dielectrics are recommended for the input
capacitor. Y5V dielectrics lose most of their capacitance
over temperature and are therefore, not recommended.
Figure 13. Current Response to a Falling Enable Signal
Figure 12. Current Response to a Rising Enable Signal
(Four Paralleled Channels)
(Four Paralleled Channels)
M9999-062909-C
MIC2841A